Семинар 20 июня 2017. В. А. Березин. Phenomenology of cosmological particle creation, Dirac sea and all that.

*by: , @ Thu, 15 Jun 2017 02:16:17 +0400*

20 июня 2017, в 12:45

Кафедра физики высоких энергий и элементарных частиц

В. А. Березин

(ИЯИ РАН, Москва)

Phenomenology of cosmological particle creation, Dirac sea and all that

Here we present a phenomenological model of cosmological particle

creation which allows to avoid the "vicious circle" when the purely

quantum treatment of the fields, which quanta are just the created

particle, requires imposing definite boundary conditions, while the

latter, in turn, requires solving the gravitational equations with the

created particles together with the expectation values of these very

fields as their source. We are using the hydrodynamical description of

the created particles (in Eulerian coordinates) incorporating the

"creation law" straight into the action integral with the corresponding

Lagrange multiplier. Adopting the famous result that the particle

production rate is proportional to the square of the Weyl tensor, we

showed that this induces the appearance of conformal gravity action

integral. It was tempting, then, to demand the local conformal

invariance as the fundamental law. Such a requirement, as was shown, has

very far-going consequences. It concerns, first of all, the scalar field

(terribly needed in the Standard Model). Writing for the scalar field

the simplest possible action (kinetic + mass terms only) we showed that

the local conformal invariance requires introduction of the curvature

scalar and, at the same time, the identification of this field with one

of the possible conformal factors, and such an identification induces

the self-interaction arising from the mass term and playing the role of

the quintessence. Thus, we have got the Weyl-Einstein - dilaton gravity

with the cosmological term almost for nothing. Then, we considered the

vacuum equations in our model. It is shown that, beside the "empty

vacuum" (i.e., no particles and no particle creation) which is rather

poor, there may exist the "dynamical vacuum" when particle with both

positive and negative energies are continuously creating leaving the

total energy-momentum tensor zero. This is just the Dirac sea. The

vacuum equations in this case are especially nice - the linear

combination of the Bach tensor, the Einstein tensor and the cosmological

constant.